/// <summary>
/// Method that computes number of components in a graph and assigns
/// component number to every vertex.
/// </summary>
public void GetNumberOfComponents()
{
UFvertex [] uf = new UFvertex[graph.Count];
HashSet <int> comps = new HashSet <int>();
int [] components = new int[graph.Count];
for (int i = 0; i < graph.Count; i++)
{
uf[i] = new UFvertex(i, 1);
}
foreach (Edge e in Edges)
{
UnionFind.Union(e, uf);
}
foreach (UFvertex uv in uf)
{
for (int i = 0; i < uf.Length; i++)
{
comps.Add(uf[i].parent);
components[i] = uf[i].parent;
}
}
NumberOfComponents = comps.Count;
ComponentNumbers = components;
return(comps.Count);
}
/// <summary>
/// This method finds minimum spanning tree of an input graph
/// </summary>
/// <returns>
/// It returns instance of SpanningTreeInfo class, that contains
/// cost of MST and MST graph itself.
/// </returns>
/// <param name="g"> Is a graph in which MST will be found </param>
public static SpanningTreeInfo GetSpanning(Graph g)
{
List <List <Edge> > graph = g.graph;
// List of all graph edges
List <Edge> edges = new List <Edge>();
// For every vertex there is union-find representation for it
UFvertex [] parents = new UFvertex[graph.Count];
// Actual MST
Graph mst = new Graph();
// Edges that are used in MST
long totalCost = 0;
for (int i = 0; i < graph.Count; i++)
{
mst.AddVertex();
parents[i] = new UFvertex(i, 1);
}
// Get all edges
foreach (List <Edge> l in graph)
{
foreach (Edge e in l)
{
edges.Add(e);
}
}
// Sort all edges
edges.Sort(comparison);
foreach (Edge e in edges)
{
/* If union happened, that means that current edge connected
* together two components of a graph so it is added into MST */
if (UnionFind.Union(e, parents))
{
mst.AddEdge(e.source, e.destination, e.weight);
totalCost += e.weight;
/* Console.WriteLine("Hrana z {0} do {1}", e.source, e.destination); */
}
}
return(new SpanningTreeInfo(mst, totalCost));
}
